Process of manufacturing a battery system assembly using the battery system assembly press

ABSTRACT

A method of manufacturing a battery pack is disclosed. The method includes placing first and second sets of battery cells in first and second battery cell holders of a battery system assembly press, placing a cooling duct in a gap between the first and second sets of battery cells, and applying a first and second forces to the first and second sets of battery cells to cause the first and second sets of battery cells to respectively press against first and second sides of the cooling duct. The method also includes, while applying the first and second forces, placing the first and second plurality of battery cells in a first tray configured to hold the first and second plurality of battery cells.

BACKGROUND

An electric vehicle uses one or more electric motors powered byelectrical energy stored in a rechargeable battery system. Lithium-basedbatteries are often chosen for their high power and energy density. Inorder to ensure that an electric vehicle operates efficiently andsafely, the temperature of the battery system must be maintained withina defined range of optimal temperatures. The coolant system of electricvehicle can be physically extended to the battery system to removeexcess heat, thereby increasing the service life of the battery systemand increasing the distance that can be traveled on a single charge.

As the popularity of electric vehicles increases, efficiency in themanufacturing process will become more important. Processes and devicesthat decrease the cost of manufacturing battery systems whilesimultaneously increasing their reliability and safety will be key tomeeting customer demands. Specifically, there is a need for processesand devices that ensure reliable electrical connections betweenindividual battery cells, that efficiently cool the battery system, andthat aid in the manufacturing process of assembling the thousands ofindividual battery cells into modular systems that can be installed andreplaced when necessary.

BRIEF SUMMARY OF THE INVENTION

Aspects of the present disclosure relate to battery systems and methodsof making and/or manufacturing the battery systems, and some aspects ofthe present disclosure relate to removably fixable attachments betweentrays configured to house battery cells of a rechargeable batterysystem.

One inventive aspect is a method of manufacturing a battery pack for anelectric vehicle. The method includes placing a first plurality ofbattery cells in a first battery cell holder of a battery systemassembly press, placing a second plurality of battery cells in a secondbattery cell holder of the battery system assembly press, and placing acooling duct in a gap between the first and second pluralities ofbattery cells. The method also includes applying a first force to thefirst plurality of battery cells and a second force to the secondplurality of batteries, where the first and second forces cause thefirst and second pluralities of battery cells to press against thecooling duct, where the first plurality of battery cells is pressedagainst a first side of the cooling duct, where the second plurality ofbattery cells is pressed against a second side of the cooling duct, andwhere the first side of the cooling duct is opposite the second side ofthe cooling duct. The method also includes, while applying the first andsecond forces, placing the first and second plurality of battery cellsin a first tray configured to hold the first and second plurality ofbattery cells.

In some embodiments, applying the first and second forces to the firstand second plurality of battery cells causes the cooling duct to deform.

In some embodiments, the gap between the first and second pluralities ofbattery cells corresponds with a gap between the first and secondbattery cell holders.

In some embodiments, the first force is applied to the first pluralityof batteries battery cells through the first battery cell holder, andthe second force is applied to the second plurality of battery cellsthrough the second battery cell holder.

In some embodiments, the first force is applied to the first batterycell holder with a first slide, and the second force is applied to thesecond battery cell holder with a second slide.

In some embodiments, the first and second forces cause first slide andthe first battery cell holder to move with respect to the second slideand the second battery cell holder.

In some embodiments, the first and second slides and the first andsecond battery cell holders are slidably connected with at least onerail, and the first and second forces cause the first slide and thefirst battery cell holder to slide along the rail.

In some embodiments, the first and second forces cause the firstplurality of batteries to move with respect to the second plurality ofbatteries, such that the size of the gap between the first and secondplurality of batteries is reduced.

In some embodiments, the method also includes placing the first andsecond plurality of battery cells in a second tray configured to holdthe first and second plurality of battery cells.

In some embodiments, at least one of the first and second trays isconfigured to apply a force to the first and second plurality of batterycells which causes the first and second plurality of battery cells to bepressed against the cooling duct.

In some embodiments, the method also includes removing the first andsecond pluralities of battery cells from the first and second batterycell holders prior to placing the first and second plurality of batterycells in the second tray.

In some embodiments, the method also includes attaching the upper trayto the lower tray.

In some embodiments, the method also includes electrically connectingthe first plurality of battery cells to at least one first busbar, andelectrically connecting the second plurality of battery cells to atleast one second busbar.

Another inventive aspect is a battery system assembly press, includingone or more rails, and first and second slides, each slidably connectedto the one or more rails. The battery system also includes a pluralityof battery cell holders each slidably connected to the one or more railsbetween the first and second slides, where the battery cell holders areeach configured to hold a plurality of battery cells.

In some embodiments, the first and second slides have topologicalfeatures which mate with corresponding features in the one or more railssuch that the first and second slides are slidably connected to the oneor more rails.

In some embodiments, the battery cell holders have topological featureswhich mate with corresponding features in the one or more rails suchthat the battery cell holders are slidably connected to the one or morerails.

In some embodiments, the battery cell holders are each configured tohold two rows of battery cells.

In some embodiments, the two rows of battery cells are offset from oneanother such that the centers of the battery cells of one row arealigned with points between the battery cells of the other row.

In some embodiments, the battery cell holders are each configured tohold the battery cells such that the battery cells touch each other.

In some embodiments, the rails are configured to be fixed to a table.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings, wherein like reference numerals are usedthroughout the several drawings to refer to similar components. In someinstances, a sub-label is associated with a reference numeral to denoteone of multiple similar components. When reference is made to areference numeral without specification to an existing sub-label, it isintended to refer to all such multiple similar components.

FIG. 1 illustrates a simplified diagram of an electric vehicle with arechargeable battery system, according to some embodiments.

FIG. 2 illustrates a lithium-based battery that may be used in electricvehicles, according to some embodiments.

FIG. 3 is an illustration of a battery pack.

FIGS. 4A-4G is a series of views illustrating a process of manufacturinga battery pack.

FIG. 5 is a flowchart illustrating an embodiment of a process formanufacturing a rechargeable battery pack.

DETAILED DESCRIPTION OF THE INVENTION

Described herein are embodiments for providing methods of assembling arechargeable battery system. The battery systems rechargeable batterysystems included battery cells and a cooling duct configured to transferheat away from the battery cells. The methods provide for effectivethermal contact between the cooling duct and the battery cells.

In some embodiments, the cooling duct and the battery cells are looselyassembled, and are subsequently pressed mechanically pressed togetherwith a battery system assembly press so as to generate good contactbetween the cooling duct and the battery cells.

FIG. 1 illustrates a simplified diagram 100 of an electric vehicle 102with a rechargeable battery system 104, according to some embodiments.The rechargeable battery system 104 may be comprised of one or morebattery modules or packs 106. A battery pack may be comprised of aplurality of individual battery cells that are electrically connected toprovide a particular voltage/current to the electric vehicle 102. Insome embodiments, the battery cells forming the battery pack can bearranged in one or several rows of battery cells. Depending on theembodiment, the electric vehicle 102 may include hybrid vehicles thatoperate using both fuel combustion and stored electric power, as well asfully electric vehicles that operate entirely from stored electricpower.

The rechargeable battery system 104 represents a major component of theelectric vehicle 102 in terms of size, weight, and cost. A great deal ofeffort goes into the design and shape of the rechargeable battery system104 in order to minimize the amount of space used in the electricvehicle 102 while ensuring the safety of its passengers. In someelectric vehicles, the rechargeable battery system 104 is located underthe floor of the passenger compartment as depicted in FIG. 1. In otherelectric vehicles, the rechargeable battery system 104 can be located inthe trunk or in the hood areas of the electric vehicle.

While a smaller number of larger battery cells could be moreenergy-efficient, the size and cost of of these larger batteries areprohibitive. Furthermore, larger batteries require more contiguousblocks of space in the electric vehicle 102. This prevents largerbatteries from being stored in locations such as the floor of thepassenger compartment as depicted in FIG. 1. Therefore, some embodimentsuse a large number of smaller battery cells that are coupled together togenerate electrical characteristics that are equivalent to single largercells. The smaller cells may be, for example, the size of traditionalAA/AAA batteries, and may be grouped together to form a plurality ofbattery packs 106. Each battery pack may include a large number ofindividual battery cells. In one embodiment, 700 individual lithium-ionbatteries are joined together to form each of a number of single batterypacks 106 a, 106 b, 106 c, and 106 d, and the rechargeable batterysystem 104 may include the four battery packs 106 a, 106 b, 106 c, and106 d. In some embodiments, the rechargeable battery system 104 includeeight battery packs, ten battery packs, sixteen battery packs, oranother number of battery packs, connected in parallel or series untilthe electrical requirements of the electric vehicle 102 are satisfied.The individual battery cells included in each battery pack 106 may totalin the thousands for a single electric vehicle 102.

In some embodiments, the rechargeable battery system 104, andspecifically one or several of the battery packs 106 can be connected toa heat exchanger 108 that can be a part of a cooling system 110. In someembodiments, the cooling system 110 can be part of the rechargeablebattery system 104 and in some embodiments, the cooling system 110 canbe separate from the rechargeable battery system 104. The cooling system110 can include connecting lines 112 that can fluidly connec the heatexchanger 108 to one or several of the battery packs 106. The connectinglines 112 can include an inlet line 114 and an outlet line 116. Theinlet line 114 can transport a cooling fluid, such as a refrigerant tothe rechargeable battery system 104 and/or to one or several batterypacks 106. In some embodiments, the cooling fluid can be contained inthe cooling system 110, in the rechargeable battery system 104, and/orin one or several battery packs 106.

FIG. 2 illustrates a diagram 200 of a lithium-based battery 202 that maybe used in electric vehicles, according to some embodiments. As usedherein, the terms “battery”, “cell”, and “battery cell” may be usedinterchangeably to refer to any type of individual battery element usedin a battery system. The batteries described herein typically includelithium-based batteries, but may also include various chemistries andconfigurations including iron phosphate, metal oxide, lithium-ionpolymer, nickel metal hydride, nickel cadmium, nickel-based batteries(hydrogen, zinc, cadmium, etc.), and any other battery type compatiblewith an electric vehicle. For example, some embodiments may use the 6831NCR 18650 battery cell from Panasonic®, or some variation on the 18650form-factor of 6.5 cm×1.8 cm and approximately 45 g. The battery 202 mayhave at least two terminals. In some embodiments, a positive terminal204 may be located at the top of the battery 202, and a negativeterminal 206 may be located on the opposite bottom side of the battery202.

In some embodiments, some or all of the battery cells forming a batterypack 106 can be oriented in the same direction. In other words, thepositive terminal of each of the individual battery cells may face in anupward (or downward) direction relative to the battery pack, and each ofthe negative terminals faces in a downward direction. In otherembodiments, this need not be the case. Alternating rows of individualbattery cells may be oriented in opposite direction such that thepositive terminal of a first row is oriented in the up direction and thepositive terminal of a second row is oriented in the downward direction.The orientation pattern for individual battery cells may vary withoutlimitation. For example, every other battery cell in a row be orientedin opposite directions. In some embodiments, one half of the batterypack may have battery cells oriented in one direction, while the otherhalf of the battery pack has cells oriented in the opposite direction.In any of these cases, connections may need to be established betweenbatteries oriented in opposite directions or between batteries orientedin the same direction.

In order to make electrical connections between battery cells, a busbarmay be used. As used herein, the term “busbar” refers to any metallicconductor that is connected to a plurality of individual battery cellterminals in order to transmit power from the individual battery cellsto the electrical system of the electric vehicle. In some embodiments,the busbar may comprise a flat metallic sheet that is positioned on thetop or the bottom of the battery pack. In some embodiments, the metallicsheet may cover an entire top or bottom of the battery pack, while inother embodiments, the busbar may comprise a strip that is longer thanit is wide to interface with a single row of battery cells.

FIG. 3 is an illustration of battery pack 300, which includes batterycells 310, cooling duct 320, lower tray 330, and upper tray 340.

Battery cells 310 are arranged so as to engage indentations in lowertray 330 and upper tray 340. Because of the indentations, lower tray 330and upper tray 340 provide mechanical support which resists lateral orshearing forces. In some embodiments, lower tray 330 and upper tray 340are nonconductive. For example lower tray 330 and upper tray 340 may beformed with an injection molded plastic.

In addition, battery cells 310 are arranged so as to be supported bycooling duct 320. Cooling duct 320 includes fluid channels, throughwhich a cooling fluid may be circulated so as to provide a path throughwhich heat may be removed from the battery cells 310. Cooling duct 320also provides mechanical support resisting lateral or shearing forces.In addition, cooling duct 320 provides mechanical support to the batterycells during manufacturing, as discussed further below.

One or more busbars (not shown) may be further mechanically connectedwith upper tray 340. For example, the busbars may be glued or welded toupper tray 34—so as to electrically contact the battery cells throughholes 344.

One or more busbars (not shown) may be further mechanically connectedwith lower tray 330. For example, the busbars may be glued or welded tolower tray 330 so as to electrically contact the battery cells throughholes in lower tray 330.

The busbars may include a plurality of contacts configured toelectrically connect one or several portions and/or layers of thebusbars with one or several battery cells 310, and specifically to theterminals of one or several battery cells 310. In some embodiments, oneor several of the plurality of contacts can be electrically connectedwith one or several conductive layers of the busbar and/or with one orseveral conductive materials forming the busbar.

The battery cells 310 and the busbars may be oriented so as to provideany desired combination of serial and parallel connections among thebatteries.

FIGS. 4A-4G is a series of views illustrating a process of manufacturinga battery pack, such as battery pack 300 of FIG. 3.

FIG. 4A is an illustration of battery system assembly press 400. Batterysystem assembly press 400 includes slides 410, battery cell holders 420,and rails 430.

Slides 410 slidably engage rails 430 such that slides 410 are fixed torails 430 and can slide along rails 430 in response to a lateral forceapplied thereto. For example, the rail 430 side of slides 410 may havetopological features which mate with corresponding features in rails 430such that the separation between slides 410 and rails 430 is limited andsuch that the slides 410 are free to slide along rails 430 in responseto the lateral force applied thereto.

Battery cell holders 420 are each configured to hold a number of batterycells. For example, battery cell holders 420 may each be configured tohold two rows of battery cells. In some embodiments, the two rows areoffset from one another such that the centers of the battery cells ofone row are aligned with points between the battery cells of the otherrow. In some embodiments, the battery cells of each row are held by thebattery cell holders 420 so as to be touching one another. In someembodiments, the battery cells of one row are held by the battery cellholders 420 so as to touch the battery cells of the other row.

Battery cell holders 420 slidably engage rails 430 such that batterycell holders 420 are fixed to rails 430 and can slide along rails 430 inresponse to a lateral force applied thereto. For example, the rail 430side of battery cell holders 420 may have topological features whichmate with corresponding features in rails 430 such that the separationbetween battery cell holders 420 and rails 430 is limited and such thatthe battery cell holders 420 are free to slide along rails 430 inresponse to the lateral force applied thereto.

In use, rails 430 may be fixed to a substantially immovable object, suchas a table bolted to a floor. A lateral force may be applied to each ofslides 410. In response to the forces applied thereto, slides 410 slidealong rails 430 toward one another. The movement of slides 410 towardone another causes the battery cell holders 420 to slide along rails 430until the battery cell holders 420 of each adjacent pair of battery cellholders 420 are pressed together.

FIG. 4B is an illustration of battery system assembly press 400 havingbattery cell holders 420 populated with battery cells 510. As shown,each battery cell holder 420 holds a number of battery cells, where eachof the battery cells 510 is in one of the indentations 434 of thebattery cell holders 420, as shown in FIG. 4A.

As shown, at this point, the slides 410 and the battery cell holders 420are spaced apart from one another.

FIG. 4C is an illustration of battery system assembly press 400 havingbattery cell holders 420 populated with battery cells 510 and havingcooling duct 520 routed among the battery cells 510. Battery cells 510engage and are held in place by the indentations 434 of the battery cellholders 420, and cooling duct 520 provides additional mechanical supportto the battery cells 510 during manufacturing, such that the batterycells 510 are less likely to be removed from battery cell holders 420by, for example, lateral or other forces. Cooling duct 320 includesfluid channels, through which a cooling fluid may be circulated so as toprovide a path through which heat may be removed from the battery cells510.

As shown, at this point, the slides 410 and the battery cell holders 420are spaced apart from one another.

FIG. 4D is an illustration of battery system assembly press 400 havingbattery cell holders 420 populated with battery cells 510, havingcooling duct 520 routed among the battery cells 510, and after batterysystem assembly press 400 has been actuated. As a result of lateralforces being applied to slides 410 in opposite directions, slides 410have been pressed and have moved toward one another, pinching thebattery cell holders 420, the battery cells 510, and the cooling duct520 between the slides 410. As a result, each segment of the coolingduct 520 running between battery cells 510 is pressed between batterycells 510 on opposing sides of cooling duct 520. Depressing forceexerted by the battery cells 510 on cooling duct 520 causes good thermalcontact between the battery cells 510 and the cooling duct 520. Asshown, portions of cooling duct 520 outside the regions occupied bybattery cells 510 are deformed as a result of the pressing action of thelateral forces applied to slides 410.

FIG. 4E is an illustration of battery system assembly press 400 havingbattery cell holders 420 populated with battery cells 510, havingcooling duct 520 routed among the battery cells 510, after the batterycells 510 and the cooling duct 520 have been pressed together, and afterlower tray 530 has been placed on the battery cells 510.

Lower tray 530 has been placed on battery cells 510 such that each ofthe battery cells 510 engages an indentation in lower tray 530configured to receive one or more of the battery cells 510. As shown,lower tray 530 includes a plurality of holes each aligned so as toprovide access to either a positive or a negative electrode of thebattery cells 510, according to the orientation of each of the batterycells 510.

FIG. 4F is an illustration of battery system 500 partially formed withbattery system assembly press 400. As a result of the actuation ofbattery system assembly press 400, battery cells 510 are pressed againstcooling duct 520 routed among the battery cells 510, and has lower tray530 placed on the far side of the battery cells 510, as viewed.

FIG. 4G is an illustration of of battery system 500 partially formed. Asshown, upper tray 540 has been placed on battery cells 510 such thateach of the battery cells 510 engages an indentation in the upper tray540 configured to receive one or more of the battery cells 510. Asshown, upper tray 540 includes a plurality of holes each aligned so asto provide access to either a positive or a negative electrode of thebattery cells 510, according to the orientation of each of the batterycells 510.

Once the battery cells 510 are housed in lower tray 530 and upper tray540, as shown in FIG. 4G, one or more busbars may be attached to lowertray 530 on the side opposite the battery cells 510. The one or morebusbars may have contacts aligned with the holes in lower tray 530, suchthat when the one or more busbars are attached to lower tray 530, theone or more busbars are electrically connected to the battery cells 510via the contacts.

Once the battery cells 510 are housed in lower tray 530 and upper tray540, as shown in FIG. 4G, one or more busbars may be attached to uppertray 540 on the side opposite the battery cells 510. The one or morebusbars may have contacts aligned with the holes in upper tray 540, suchthat when the one or more busbars are attached to upper tray 540, theone or more busbars are electrically connected to the battery cells 510via the contacts.

In some embodiments, the one or more busbars of the lower tray 530 areattached to the lower tray 530 prior to the lower tray 530 receiving orbeing connected to the battery cells 510. Likewise, in some embodiments,the one or more busbars of the upper tray 540 are attached to the uppertray 540 prior to the upper tray 540 receiving or being connected to thebattery cells 510.

FIG. 5 is a flowchart illustrating one embodiment of a process 500 formanufacturing a rechargeable battery pack, such as those discussedherein. The method can include, for example, a process for manufacturingone or several battery packs 106 of rechargeable battery pack system104, discussed above with reference to FIG. 1.

The process begins at block 550, and may include placing a plurality ofbattery cells in each of a plurality of battery cell holders of abattery system press assembly. The battery cells may be placed so as toeach have an orientation corresponding with a desired configuration ofserial and parallel connections among the batteries.

At 560, the process 500 also includes routing a cooling duct among thebattery cells. For example, the battery cells may be placed in a seriesof rows in the battery cell holders, where each of the rows is spacedapart from an adjacent row by a gap, and the cooling ducts may be routedamong the battery cells in the gaps. In some embodiments, the coolingduct is routed between each pair of adjacent rows of the battery cells.In some embodiments, the cooling duct is routed between every other pairof adjacent rows of the battery cells. Other arrangements areadditionally used.

In some embodiments, each battery cell holder of the battery systempress assembly holds two rows of battery cells, and the cooling duct isrouted between each battery cell holder.

At 570, the process 500 also includes pressing the battery cell holderstogether such that the cooling duct segments routed between adjacentrows of battery cells is compressed between the adjacent rows of batterycells. As a result, a good thermal connection is formed between thecooling duct and each of the battery cells of the adjacent rows ofbattery cells.

At 580, The process 500 also includes placing the battery cells in alower tray. In some embodiments, the battery cells are fixed to thelower tray with, for example, a glue, an epoxy, or another fixingmechanism. In some embodiments, the battery cells are not fixed to thelower tray. The battery cells are placed in the lower tray such that thebattery cells engage and are held in place by the indentations of thelower tray. In addition, the battery cells are placed in the lower traysuch that the electrical terminals of the battery cells near the lowertray are aligned with holes in the lower tray so as to be accessible toan electrical contact.

At 590, The process 500 also includes placing the battery cells in anupper tray. In some embodiments, the battery cells are removed from thebattery cell holders prior to placing the battery cells in the uppertray. In some embodiments, the battery cells are fixed to the upper traywith, for example, a glue, an epoxy, or another fixing mechanism. Insome embodiments, the battery cells are not fixed to the upper tray. Thebattery cells are placed in the upper tray such that the battery cellsengage and are held in place by the indentations of the upper tray. Inaddition, the battery cells are placed in the upper tray such that theelectrical terminals of the battery cells near the upper tray arealigned with holes in the upper tray so as to be accessible to anelectrical contact.

In some embodiments, once the batteries are placed in the lower tray andthe upper tray, either or both of the lower tray and the upper trayexert forces on the battery cells which cause the battery cells to bepressed against the cooling duct.

The process 500 may additionally include attaching the upper tray to thelower tray. The upper tray may be attached to the lower tray such thatan extension between upper tray and lower tray connects the upper trayand the lower tray. In some embodiments, the extension connects theupper tray and a lower tray with, for example, a glue, a weld, athreaded fastener, or another fixing mechanism.

The extension may also provide mechanical support protecting the batterycells from forces resulting from, for example, vertical impact. Forexample, battery pack may be configured such that the extensiontransfers a vertical force between the upper and lower trays and with noor substantially no vertical force being transferred by the batterycells themselves.

The process 500 may additionally include attaching busbars to the uppertray and to the lower tray. The busbars may be attached to the upper andlower trays such that contacts of the busbars form of electricalconnections with the battery cells. In some embodiments, the busbars areconnected to the upper and lower trays prior to the upper and lowertrays receiving the battery cells. In some embodiments, the busbars areconnected to the upper and lower trays after the upper and lower trayshave received the battery cells.

In alternative embodiments, the battery cells are fixed to the busbars,for example, with a glue, or another attachment mechanism, such as aweld. In such embodiments, the battery cells may additionally beattached to the upper tray and/or lower tray by a glue or anotherattachment mechanism. In some embodiments, the battery cells are heldagainst the upper tray and/or lower tray by the extension attaching theupper tray to the lower tray, and are not otherwise attached to theupper tray and/or lower tray. In some embodiments, one or more of thebusbars exerts forces on the battery cells which cause the battery cellsto be pressed against the cooling duct.

In alternative embodiments, the battery cells are not fixed to one orboth of the upper and lower trays. In such embodiments, the upper traymay be connected to the lower tray by a glue or another attachmentmechanism. In some embodiments, the battery cells are held against theupper tray and/or lower tray by the attachment mechanism attaching theupper tray to the lower tray, and are not otherwise attached to theupper tray and/or lower tray.

The process 500 may additionally include electrically connecting therechargeable battery system with a motor configured to provide power tothe vehicle.

It should be appreciated that the specific steps illustrated in FIG. 5provide particular methods of providing a rechargeable battery systemand/or a battery pack for an electric vehicle according to variousembodiments of the present invention. Other sequences of steps may alsobe performed according to alternative embodiments. For example,alternative embodiments of the present invention may perform the stepsoutlined above in a different order. Moreover, the individual stepsillustrated in FIG. 5 may include multiple sub-steps that may beperformed in various sequences as appropriate to the individual step.Furthermore, additional steps may be added or removed depending on theparticular applications. One of ordinary skill in the art wouldrecognize many variations, modifications, and alternatives.

In the foregoing description, for the purposes of explanation, numerousspecific details were set forth in order to provide a thoroughunderstanding of various embodiments of the present invention. It willbe apparent, however, to one skilled in the art that embodiments of thepresent invention may be practiced without some of these specificdetails. In other instances, well-known structures and devices are shownin block diagram form.

The foregoing description provides exemplary embodiments only, and isnot intended to limit the scope, applicability, or configuration of thedisclosure. Rather, the foregoing description of the exemplaryembodiments will provide those skilled in the art with an enablingdescription for implementing an exemplary embodiment. It should beunderstood that various changes may be made in the function andarrangement of elements without departing from the spirit and scope ofthe invention as set forth in the appended claims.

Specific details are given in the foregoing description to provide athorough understanding of the embodiments. However, it will beunderstood by one of ordinary skill in the art that the embodiments maybe practiced without these specific details. For example, circuits,systems, networks, processes, and other components may have been shownas components in block diagram form in order not to obscure theembodiments in unnecessary detail. In other instances, well-knowncircuits, processes, algorithms, structures, and techniques may havebeen shown without unnecessary detail in order to avoid obscuring theembodiments.

Also, it is noted that individual embodiments may have been described asa process which is depicted as a flowchart, a flow diagram, a data flowdiagram, a structure diagram, or a block diagram. Although a flowchartmay have described the operations as a sequential process, many of theoperations can be performed in parallel or concurrently. In addition,the order of the operations may be re-arranged. A process is terminatedwhen its operations are completed, but could have additional steps notincluded in a figure. A process may correspond to a method, a function,a procedure, a subroutine, a subprogram, etc. When a process correspondsto a function, its termination can correspond to a return of thefunction to the calling function or the main function.

In the foregoing specification, aspects of the invention are describedwith reference to specific embodiments thereof, but those skilled in theart will recognize that the invention is not limited thereto. Variousfeatures and aspects of the above-described invention may be usedindividually or jointly. Further, embodiments can be utilized in anynumber of environments and applications beyond those described hereinwithout departing from the broader spirit and scope of thespecification. The specification and drawings are, accordingly, to beregarded as illustrative rather than restrictive.

1. A method of manufacturing a battery pack, the method comprising: placing a first plurality of battery cells in a first battery cell holder of a battery system assembly press; placing a second plurality of battery cells in a second battery cell holder of the battery system assembly press; placing a cooling duct in a gap between the first and second pluralities of battery cells; applying a first force to the first plurality of battery cells and a second force to the second plurality of batteries, wherein the first and second forces cause the first and second pluralities of battery cells to press against the cooling duct, wherein the first plurality of battery cells is pressed against a first side of the cooling duct, where the second plurality of battery cells is pressed against a second side of the cooling duct, and wherein the first side of the cooling duct is opposite the second side of the cooling duct; and while applying the first and second forces, placing the first and second plurality of battery cells in a first tray configured to hold the first and second plurality of battery cells, wherein the first force is applied to the first plurality of batteries battery cells through the first battery cell holder, and wherein the second force is applied to the second plurality of battery cells through the second battery cell holder.
 2. The method of claim 1, wherein applying the first and second forces to the first and second plurality of battery cells causes the cooling duct to deform.
 3. The method of claim 1, wherein the gap between the first and second pluralities of battery cells corresponds with a gap between the first and second battery cell holders.
 4. (canceled)
 5. The method of claim 4, wherein the first force is applied to the first battery cell holder with a first slide, and wherein the second force is applied to the second battery cell holder with a second slide.
 6. The method of claim 5, wherein the first and second forces cause first slide and the first battery cell holder to move with respect to the second slide and the second battery cell holder.
 7. The method of claim 6, wherein the first and second slides and the first and second battery cell holders are slidably connected with at least one rail, and wherein the first and second forces cause the first slide and the first battery cell holder to slide along the rail.
 8. The method of claim 1, wherein the first and second forces cause the first plurality of batteries to move with respect to the second plurality of batteries, such that the size of the gap between the first and second plurality of batteries is reduced.
 9. The method of claim 1, further comprising placing the first and second plurality of battery cells in a second tray configured to hold the first and second plurality of battery cells.
 10. The method of claim 9, wherein at least one of the first and second trays is configured to apply a force to the first and second plurality of battery cells which causes the first and second plurality of battery cells to be pressed against the cooling duct.
 11. The method of claim 9, further comprising removing the first and second pluralities of battery cells from the first and second battery cell holders prior to placing the first and second plurality of battery cells in the second tray.
 12. The method of claim 9, further comprising attaching the upper tray to the lower tray.
 13. The method of claim 9, further comprising: electrically connecting the first plurality of battery cells to at least one first busbar; and electrically connecting the second plurality of battery cells to at least one second busbar. 14.-20. (canceled)
 21. A method of manufacturing a battery pack, the method comprising: placing a first plurality of battery cells in a first battery cell holder of a battery system assembly press; placing a second plurality of battery cells in a second battery cell holder of the battery system assembly press; placing a cooling duct in a gap between the first and second pluralities of battery cells; applying a first force to the first plurality of battery cells and a second force to the second plurality of batteries, wherein the first and second forces cause the first and second pluralities of battery cells to press against the cooling duct, wherein the first plurality of battery cells is pressed against a first side of the cooling duct, where the second plurality of battery cells is pressed against a second side of the cooling duct, and wherein the first side of the cooling duct is opposite the second side of the cooling duct; and while applying the first and second forces, placing the first and second plurality of battery cells in a first tray configured to hold the first and second plurality of battery cells, wherein the first and second forces cause the first plurality of batteries to move with respect to the second plurality of batteries, such that the size of the gap between the first and second plurality of batteries is reduced.
 22. The method of claim 21, wherein applying the first and second forces to the first and second plurality of battery cells causes the cooling duct to deform.
 23. The method of claim 21, wherein the gap between the first and second pluralities of battery cells corresponds with a gap between the first and second battery cell holders.
 24. The method of claim 21, further comprising placing the first and second plurality of battery cells in a second tray configured to hold the first and second plurality of battery cells.
 25. The method of claim 21, wherein at least one of the first and second trays is configured to apply a force to the first and second plurality of battery cells which causes the first and second plurality of battery cells to be pressed against the cooling duct.
 26. The method of claim 21, further comprising removing the first and second pluralities of battery cells from the first and second battery cell holders prior to placing the first and second plurality of battery cells in the second tray.
 27. The method of claim 21, further comprising attaching the upper tray to the lower tray.
 28. The method of claim 21, further comprising: electrically connecting the first plurality of battery cells to at least one first busbar; and electrically connecting the second plurality of battery cells to at least one second busbar.
 29. A method of manufacturing a battery pack, the method comprising: placing a first plurality of battery cells in a first battery cell holder of a battery system assembly press; placing a second plurality of battery cells in a second battery cell holder of the battery system assembly press; placing a cooling duct in a gap between the first and second pluralities of battery cells; applying a first force to the first plurality of battery cells and a second force to the second plurality of batteries, wherein the first and second forces cause the first and second pluralities of battery cells to press against the cooling duct, wherein the first plurality of battery cells is pressed against a first side of the cooling duct, where the second plurality of battery cells is pressed against a second side of the cooling duct, and wherein the first side of the cooling duct is opposite the second side of the cooling duct; while applying the first and second forces, placing the first and second plurality of battery cells in a first tray configured to hold the first and second plurality of battery cells; and placing the first and second plurality of battery cells in a second tray configured to hold the first and second plurality of battery cells.
 30. The method of claim 29, wherein applying the first and second forces to the first and second plurality of battery cells causes the cooling duct to deform.
 31. The method of claim 29, wherein the gap between the first and second pluralities of battery cells corresponds with a gap between the first and second battery cell holders. 